Systems and methods for contaminant removal from a microalgae culture

ABSTRACT

Systems and methods for the removal of contaminants from and transferring gasses within a liquid culture microalgae and/or cyanobacteria comprise an inlet tube, a pump, a gas injector, a vertical chamber, and/or a collection container that promotes the production of foam in the microalgae culture, wherein the gasses may be added to or removed from the liquid culture.

CROSS-REFERENCES TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 61/578,533, filed Dec. 21, 2011, and incorporates thedisclosure of the application by reference.

BACKGROUND

Microalgae cultures within a growing vessel comprise a number ofundesirable contaminant or foreign substances besides the primary algaetype algae type intended to be grown and harvested. These undesirablesubstances may comprise pollutants, growth inhibitors, predators,competitors, detritus, dirt and other suspended or settled solids, andclumped algae. The growth inhibitors may comprise, but are not limitedto, algae metabolites, cell debris, bacteria, coliform bacteria, fungi,detrital matter, dissolved organic matter, fecal matter, and othermicro-particles. The competitors and predators may comprise an invasivealgae type other than the primary algae type of the culture, andzooplankton that feed on phytoplankton.

The growth of algae in terrestrial systems such as open ponds orbioreactors may be improved by removing contaminants from the algaeculture. Removal of contaminants from the algae culture may enhance thegrowth rate and health of the algae culture due to a decrease incompetition for nutrients, gases, and light, and a decrease insubstances that are directly and/or indirectly harmful, toxic, orpoisonous to the primary algae type.

SUMMARY

Disclosed herein is a system for the removal of contaminants from analgae culture and transfer of gasses. Specifically the system includesthe incorporation of a contaminant removal system to remove thecontaminants from the algae culture without substantially harming theprimary algae type or removing a substantial portion of the primaryalgae type. The system may include additional components such as, butnot limited to, ozone gas for increased sterilization, a device forintroducing coagulants and flocculent to a fluid, an ultraviolet lightsterilizer, an active carbon filter, an electric dewatering drum filter,a mechanical filtration device, and a centrifuge. Additionally a methodfor using the systems and apparatus is disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the present invention may be derived byreferring to the detailed description when considered in connection withthe following illustrative figures. In the following figures, likereference numbers refer to similar elements and steps throughout thefigures.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence or scale. For example, steps that may be performedconcurrently or in different order are illustrated in the figures tohelp to improve understanding of embodiments of the present invention.

The figures described are for illustration purposes only and are notintended to limit the scope of the present disclosure in any way.Various aspects of the present invention may be more fully understoodfrom the detailed description and the accompanying drawing figures,wherein:

FIG. 1 representatively illustrates an exemplary contaminant removalsystem coupled to an algae v-trough type bioreactor;

FIG. 2 is a block diagram illustrating an exemplary arrangement ofcomponents in the contaminant removal system;

FIG. 3 is a block diagram illustrating another exemplary arrangement ofcomponents in the contaminant removal system;

FIG. 4 is a block diagram illustrating yet another exemplary arrangementof components in the contaminant removal system;

FIG. 5 is a block diagram illustrating yet another exemplary arrangementof components in the contaminant removal system;

FIG. 6 is a flow chart illustrating an exemplary method of operating thecontaminant removal system in conjunction a vessel;

FIG. 7 is a graph illustrating the concentration of ash in a liquidalgae culture before and after the use of the contaminant removalsystem;

FIGS. 8A and 8B are microscopy pictures of contaminant removal systemeffluent and solid material collected by the contaminant removal system;

FIG. 9 is a graph illustrating the growth of the liquid algae cultureafter treatment with the contaminant removal system for 12 hours;

FIG. 10 is a graph illustrating the growth of the liquid algae culturein an indoor vessel after treatment with the contaminant removal systemfor 6 hours;

FIGS. 11A, 11B, and 11C are microscopy pictures of contaminant removalsystem effluent and solid material collected by the contaminant removalsystem; and

FIG. 12 is a graph illustrating the growth of the liquid algae culturetreated with ozone gas and the contaminant removal system.

DETAILED DESCRIPTION

The present invention may be described in terms of functional blockcomponents and various processing steps. Such functional blocks may berealized by any number of components configured to perform the specifiedfunctions and achieve the various results. For example, the presentinvention may employ various process steps, apparatus, systems, methods,etc. In addition, the present invention may be practiced in conjunctionwith any number of systems and methods for removing contaminants from avessel such as a bioreactor to promote the growth of an aquatic organismsuch as an algae culture in the vessel, and the system described ismerely one exemplary application for the invention. Variousrepresentative implementations of the present invention may be appliedto any type of vessel configured to contain a liquid culture of theaquatic organism. Certain representative implementations may include,for example, applying the contaminant removal system to the vessel topromote the growth of the algae culture in the vessel.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the present invention in any way. For the sake of brevity,conventional manufacturing, connection, preparation, and otherfunctional aspects of the system may not be described in detail.Furthermore, the connecting lines shown in the various figures areintended to represent exemplary functional relationships and/or stepsbetween the various elements. Many alternative or additional functionalrelationships or physical connections may be present in a practicalsystem.

Various embodiments of the invention provide methods, apparatus, andsystems for contaminant removal from a liquid algae culture in a vessel.A detailed description of various embodiments, namely a system andapparatus for contaminant removal from an algae culture in a vessel topromote the growth of a primary algal type in the algae culture, isprovided as a specific enabling disclosure that may be generalized toany application of the disclosed system and method in accordance withthe various described embodiments.

In various embodiments of the present invention, the primary algae typemay comprise any type of algae intended to be grown for harvestingpurposes within the algae culture. In some embodiments, the primaryalgae type may be harvested for use in subsequent processes that mayproduce valuable products. For example, the primary algae type may beharvested for food, food ingredients, food colorants, food dyes,nutraceuticals such as omega 3, 6, 7, and/or 9, eicosapentaenoic acid(EPA), docosahexaenoic acid (DHA), fertilizer, bioplastics, biofuel,chemical feedstock, pharmaceuticals such as vaccines and/or healthmaintenance products, and/or fuel. In one embodiment, the primary algaetype may comprise a microalgae. Microalgae may be any algae orcyanobacteria species, such as a product-excreting cyanobacteria, with adiameter of less than about 50 microns. Microalgae may have a diameterof about 0.5 microns to about 50 microns. In an exemplary embodiment,the microalgae may be Nannochloropsis, Chlorella, and/or any otherstrain with a diameter of less than about 50 microns. In variousembodiments, the algae culture containing the primary algae type may begrown in fresh water or salt water. In another embodiment, the primaryalgae type may comprise microalgae of the genus Chlorella and/or anyother microalgae strain.

In some embodiments, the primary algae type may be a product-excretingcyanobacteria. For example, the product-excreting cyanobacteria mayexcrete products such as lipids for use in fuels or bioplastics or otherapplications. The product-excreting cyanobacteria may be a geneticallymodified cyanobacteria that is engineered to enhance the production ofthe product. For example, the cyanobacteria of the genus Synechocystis,Synechococcus, Arthrospira, and the like can be genetically modified toexcrete desirable products such as alkanes, alcohols, hydrocarbons,and/or hydrogen. Some species of cyanobacteria may excrete compoundssuch as Geosmin and 2-methylisoborneol (MIB) that may degrade waterquality, while other compounds can cause clumping and/or inhibit growthof the cyanobacteria. The presence of cyanobacteria in an algae culturemay have direct and/or indirect effects on growth of the algae culture.Cyanobacteria may also be introduced to the culture to induce clumpingwhich may increase the harvesting and/or removal efficiency of the algaefrom the algae culture.

In various embodiments of the present invention, the contaminant removalsystem may be used to maintain the culture health for a cyanobacteriaproduct that may express oil or other chemicals. The contaminant removalsystem may be used to help remove both contaminants and expressedvaluable products such as oils and chemicals such that the organiccontaining valuable products may be separated from unwanted contaminantsin a downstream processing step. The contaminant removal system maypromote a longer culture viability for microalgae and/orproduct-excreting cyanobacteria growth systems such that the length oftime that an inoculation may maintain growth may be at least one oflonger than 3 days, greater than ten days, and/or greater than 30 days.In one embodiment, the range of culture viability may be from three to300 days without requiring a reseeding. In one embodiment, reseeding maycomprise removing the liquid algae culture from the vessel, cleaning thevessel, and starting a new culture with new growth media and seed (e.g.microalgae). However, a partial seeding may occur where some fresh seedis added to an aged culture at various times within the life of theculture. In one embodiment, the partial seeding may comprise addingfresh microalgae to an aged liquid algae culture 110 in the vesselwithout removing all the liquid algae culture 110 from the vessel.

Contaminant removal and separation methods may be used to decontaminateliquids such as wastewater, aquarium water for fish, and separating massor sludge from wastewater to produce a purified liquid. A purifiedliquid may comprise an originally contaminated liquid to which acontaminating substance has been removed by the application of asubstance removal and/or separation method, such as by the presentcontaminant removal system.

Various contaminant removal and separation systems and methods maycomprise mechanical filtration, application of liquid and/or solidchemicals to the liquid, electric dewatering, ultra violet (UV)sterilization, a light-emitting diode apparatus, and foam fractionationmethods. The conventional use of contaminant removal and separationmethods alone may not effectively improve the health of the algaeculture because such conventional methods may remove the primary algaetype in addition to contaminants.

The contaminants that may be removed or separated from the liquid algaemay comprise any substance found in the algae culture which is directlyor indirectly harmful to the primary algae type, such as slowing thegrowth rate of the primary algae type. For example, the contaminants maycomprise, pollutants, growth inhibitors, predators, competitors,bacteria, fecal matter, and detritus. The growth inhibitors maycomprise, but are not limited to, linoleic acid, coliform bacteria,fungi, algae metabolites, cell debris, detrital matter, dissolvedorganic matter, other organic matter, and other micro-particles. In oneembodiment, micro-particles may comprise any solids that may be in therange of about 10 to about 1000 microns in diameter. The diameter may bethe width of the micro-particle, such as the smallest axis of dimension.

The competitors and predators may comprise, but are not limited to, aninvasive algae type other than the primary algae type of the culture,zooplankton that feed on phytoplankton, or other organisms that feed onthe primary algae type. The contaminants may also comprise anysubstances that may be poisonous to the primary algae type, substancesthat promote growth of predators or competitors, substances that promotegrowth of organisms that directly reduce growth in the primary algaetype, and substances toxic to the primary algae type. In someembodiments, the contaminants may comprise coagulated microalgae cellsof the primary algae type. In another embodiment, the contaminants maycomprise invasive algae and/or microalgae types such as chain-formingcyanobacteria.

Various representative implementations of the present invention may beapplied to any vessel for the cultivation of the liquid algae culture.The liquid algae culture may comprise the algae and a liquid growthmedium for providing nutrition to the algae. Certain representativeimplementations may include, for example, a contaminant removal systemfor substance removal from the liquid algae culture and releasing atleast a portion of the liquid algae culture back into the vessel and/orinto a system for harvesting the algae culture.

In an exemplary embodiment, the contaminant removal system according tovarious aspects of the present invention may comprise an inlet tube, apump, a gas injector, a substantially vertical chamber, a collectioncontainer, and/or an outlet tube. Various embodiments of the presentinvention may further comprise one or more of a filter, an ultravioletlight sterilizer, a light-emitting diode apparatus, an electricdewatering drum, and a coagulation and flocculation device. Oneembodiment of the present invention may further comprise a system forharvesting the algae from the liquid algae culture.

The contaminant removal system may comprise systems for applyingadsorptive bubble separation methods, such as foam fractionation, to theliquid algae culture. Foam fractionation may generate a foam rich incontaminants, such as dissolved organic matter, or suspended solids fromthe liquid algae culture. Foam fractionation methods may introduce a gasin the form of small air bubbles into the liquid algae culture, whichmay create an air/water interface on the surface of the bubbles to whichsome contaminant particles may be attracted. The contaminant particlesmay comprise hydrophobic molecules including cell debris that may beattracted to the surface of the bubbles to minimize surface energy in anaqueous suspension. The contaminant particles attracted to the bubble'ssurface may bond to the bubble's surface and rise with the buoyantbubble towards the top of a substantially vertical chamber of acylindrical, conical, and/or rectangular flat shape such as one that maycontain parallel and/or interleaved sections of bubble floatationchambers such as interspersed or interleaved chambers of a secondprocess. The bubbles may become increasingly dense closer to the top ofthe substantially vertical chamber and form foam rich in the adsorbedcontaminant particles. The foam may be separated from the top of thesubstantially vertical chamber and removed using any collection method,such as a collection cup or scraper. The cleaned liquid algae culturemay be returned to the vessel.

The second process may include the use of ultraviolet (UV) or otherlight for sterilization and/or destruction of contaminants. In oneembodiment, UV or other light sterilization may not substantially harmthe primary algae type. For example, UV sterilization may kill less then20% of the primary algae type. In another embodiment, UV or other lightsterilization may kill less than 20% of the primary algae type. In yetanother embodiment, UV or other light sterilization may kill less than5% of the primary algae type.

Collection of the foam from the liquid algae culture may at least one ofimprove a growth rate and extend a lifetime of the liquid algae cultureupon returning the liquid algae culture to the vessel for continuedcultivation as compared to the growth rate and the lifetime prior tocontaminant removal. For example, in one embodiment, the entire volumeof the liquid culture in the vessel may be processed through thecontaminant removal system between about 1 to about 100 times per hourto improve the growth rate of the microalgae and/or the cyanobacteria byat least 5%.

Conventionally used foam fractionation methods implemented in fishaquariums are configured to remove substantially all of the algae fromthe water through foam fractionation with the purpose of improving thehealth of the fish. The algae present in fish aquariums are typicallyblack brush algae (Rhodophyta), brown algae (diatoms), blue green algae(cyanobacteria), Cladophora, green spot algae (Choleochaete orbicularis)and others. Additionally, conventional foam fractionation methods mayremove nutrients such as phosphates, amino acids, and other dissolvedorganic matter on which algae feed. Solid particles removed by thecontaminant removal system may range in size from about 10 to about 1000microns, such as 20 to 200 microns in diameter, wherein the diameter maybe the smallest dimension along any axis.

The number of turnovers that the liquid algae culture may spend withinthe contaminant removal system may vary according to the size of theliquid algae culture, such as once for a large liquid algae culture to200 turnovers or more. A turnover may be the number of times the volumeof the liquid algae culture cycles through the contaminant removalsystem over a unit of time, such as minutes, hours and/or days. In oneembodiment, the turnover may be calculated as the total culture volume(liters), divided by the water velocity (lpm or lph) going into thecontaminant removal system, multiplied by the time the contaminantremoval system is actively running on the liquid algae culture. In oneembodiment, the contaminant removal system may turnover the liquid algaeculture in the range of 10 to 1000 turnovers per day. The turnover ratemay range from 10 seconds to 10 hours, where the turnover rate is thetime for the full volume of the attached growth reactor to move throughthe contaminant removal system one time.

In various embodiments of the present invention, the contaminant removalsystem may be configured to remove contaminants from the liquid algaeculture, while leaving at least a substantial portion of the primaryalgae type remaining in the liquid algae culture. The contaminantremoval system may comprise a cylindrical tube or column, such as thesubstantially vertical chamber, and a collection cup to collect thefoam. A gas may be injected into the liquid algae culture, such as witha venturi gas injector or by direct gas injection, at a preselected gasflow rate. The liquid algae culture may be pumped into the substantiallyvertical chamber in a down-welling or up-welling application at apreselected liquid flow rate. In some embodiments, contaminant removalsystem may implement adsorptive bubble separation methods to separateand remove mineral ores, macroscopic particles, microscopic particles,surface-inactive ions, surface-inactive molecules, precipitate, anddissolved material that may be first absorbed on colloidal particles. Inone embodiment, the contaminant removal system may be optimized toremove contaminants and leave the algae in the liquid algae culture bymodifying the geometry of the contaminant removal system, such as thedimensions of the substantially vertical chamber, modifying the state ofthe gas in the liquid algae culture (i.e., dissolved or dispersed), thevelocity of the gas flow rate, and/or the velocity of the liquid flowrate.

Referring to FIG. 1, an exemplary contaminant removal system 100 may beconnected to a vessel 105 that may contain a liquid algae culture 110.The vessel 105 may comprise any apparatus for growing algae in a liquidgrowth medium (ie, the liquid algae culture 110) for the purpose ofharvesting the primary algae type. For example, the vessel 105 maycomprise a trough, a V-trough, a pond, a lake, an open growth system, araceway type pond, a tank, and a photobioreactor (PBR) of any shape ordesign used to grow microalgae and/or product-excreting cyanobacteria.In one embodiment, the open growth system may comprise a vessel that maybe at least partially uncovered. The open growth system may reduce orprevent the ingress of airborne solid matter such as ash. In someembodiments, the airborne solid matter may flow parallel to the opensurface of the of the open growth system. The growth medium of theliquid algae culture 110 may comprise fresh water or salt water eitheralone or in combination with any nutritional substances to supportgrowth of the algae. In one embodiment, the microalgae concentration inthe liquid algae culture 110 may range from about 0.01 g/L to about 100g/L. In another embodiment, the microalgae concentration in the liquidalgae culture 110 may range from about 0.1 g/L to about 10 g/L. Invarious embodiments of the present invention, any portion of thecontaminant removal system 100 may be positioned and/or connectedmechanically to any surface of the vessel 105 to contact the liquidalgae culture 110 in the vessel 105.

In various embodiments of the present invention, the contaminant removalsystem 100 may comprise an inlet tube 115 configured to receive theliquid algae culture 110 from the vessel 105. The inlet tube 115 maycomprise any suitable material capable of containing the liquid algaeculture 110, including but not limited to silicone or polyvinyl chloridepiping. In one embodiment, the inlet tube 115 may comprise a materialadapted to sustain the liquid algae culture 110 traveling at a highpressure. For example, in one embodiment, the high pressure may be in arange of 10 Pascal (Pa) to 10 MPa. In another embodiment, the highpressure may be in a range of 100 Pa to 1 MPa. In various embodiments,the inlet tube 115 may comprise a material that resists corrosion and/orbacterial growth.

In one embodiment, according to various aspects of the presentinvention, the inlet tube 115 may be coupled to a pump 120 wherein thepump is configured to receive the liquid algae culture 110 from thevessel 105 and propel the liquid algae culture 110 to a vertical chamber130 at a preselected liquid flow rate. In one embodiment the pump 120may be a venturi pump. The venturi pump may comprise a venturi gasinjector that may inject gas into the liquid algae culture 110 and mixthe gas with the liquid algae culture 110 to form a gas and liquidculture mixture 125 comprising a plurality of small gas bubbles tofacilitate the removal of contaminant by a foam fractionation process.In another embodiment, the pump may comprise a conventional water pumpand the inlet tube 115 may be coupled to a separate gas injector coupledto the pump 120 and configured to inject the gas into the liquid algaeculture 110 in the pump 120 at a preselected gas flow rate. In oneembodiment, the separate gas injector may comprise a compressed aircylinder (not shown). The gas and liquid culture mixture 125 may betransferred into a vertical chamber 130 configured to receive the gasand liquid culture mixture 125 from the pump 120. In one embodiment, thegas and liquid culture mixture 125 may enter the vertical chamber 130 ata first end of the vertical chamber. The gas and liquid culture mixture125 may be propelled from the first end of the vertical chamber 130 to asecond end of the vertical chamber 130. A foam 135 comprising thecontaminants may be generated when the gas and liquid culture mixture125 travels from the first end to the second end of the vertical chamber130, as described below.

In some embodiments, the vertical chamber 130 may be a substantiallyvertical cylindrical column. The vertical chamber 130 may besubstantially vertical at any suitable angle relative to the flat groundsuch that bubbles originating from the bottom of the vertical chamber130 rise to the top of the vertical chamber 130. For example, thevertical chamber 130 may be completely vertical such that the verticalchamber 130 is at a 90 degree angle as compared to the flat ground.However, the vertical chamber may be at more or less than a 90 degreeangle as compared to the flat ground.

In one embodiment, the bubbles formed in the gas and liquid culturemixture 125 by the injected gas may create an interface on the surfaceof the bubble between the liquid algae culture 110 and the gas to whichvarious particles, solids, and substances, such as contaminants, mayform an attraction and/or bond. The bubbles may rise to the top of thevertical chamber 130, carrying the bonded contaminant particles along.At the top of the vertical chamber 130, a plurality of bubbles may formthe foam 135 which may be collected in a collection container 140. Thecollection container 140 may be disposed at the second end of thevertical chamber and configured to collect the foam 135. The collectioncontainer 140 may comprise any type of container that may collect thefoam 135 from the vertical chamber 130, a foam fractionator, and/or adissolved air floatation device. For example, the collection container140 may comprise a cup, tray, tote, basket, and/or a tub. The remainingliquid algae culture 110 may then flow to the outlet tube 145 of thevertical chamber 130.

In some embodiments, the liquid algae culture 110 with reducedcontaminants flowing from the outlet tube 145 of the vertical chamber130 of the contaminant removal system 100 may follow a number ofsubsequent paths, such as, but not limited to: returning to the vessel105 through at least one of the outlet tube 145 and/or a return pipe150; harvesting of the microalgae from the liquid algae culture 110 forfurther processing, filtering, treatment, dewatering, cleaning, and/orseparation; further filtering, treatment, separation or processing by atleast one additional method before returning to the vessel 105; andfurther filtering, treatment, separation or processing by at least oneadditional method before harvesting or further processing. In oneembodiment, the entire volume of the liquid algae culture 110 exitingthe vertical chamber 130 may follow a single path. In anotherembodiment, the volume of liquid algae culture 110 may be split intofractions with the fractions following any combination of multiplepaths.

The gas injected into the liquid algae culture by the pump 120, whereinthe pump 120 is a venturi pump, or the gas injector may comprise anygas, such as air, ozone, nitrogen, flue gas, oxygen, and carbon dioxide.The type of gas used may be selected based on any suitable parametersuch as the species of algae in the algae culture, the growth stage ofthe algae, the type of contaminants in the algae culture, and/or theintended use of the contaminant removal system 100. In one embodiment,the use of air and carbon dioxide as the injected gas may operate toremove contaminants from the liquid algae culture 110 by forming bubblesfor foam fractionation without substantially harming the microalgae inthe liquid algae culture 110. In one embodiment, the gas may remain atleast partially undissolved in the liquid algae culture 110 and form thebubbles. In one embodiment, the gas may not substantially harm themicroalgae in the liquid algae culture 110 when less than about 10% ofthe microalgae are killed in one turnover of the liquid algae culture110 in the contaminant removal system 100. In another embodiment, thegas may not substantially harm the microalgae in the liquid algaeculture 110 when less than about 5% of the microalgae are killed. In yetanother embodiment, the gas may not substantially harm the microalgae inthe liquid algae culture 110 when less than about 1% of the microalgaeare killed.

In one embodiment, the use of ozone as the injected gas may not besubstantially harmful to the microalgae when ozone is used to removecontaminants and/or sterilize the liquid algae culture 110. For example,the use of ozone as the injected gas in a concentration of approximately0.01-5.0 milligrams per liter may not be substantially harmful to themicroalgae. In one embodiment, ozone may be injected into the liquidalgae culture at a concentration of approximately 0.01-1 milligram perliter. In another embodiment, the use of ozone as the injected gas maybe beneficial to the microalgae by sterilizing the water throughoxidation of organic contaminants while leaving the microalgaesubstantially unharmed. The use of ozone may kill less than 20% of themicroalgae, such as less than 10%, less than 5%, and/or less than 2% ofthe microalgae. In some embodiments, ozone may adversely affectcontaminants to a greater degree than the microalgae and/or theproduct-excreting cyanobacteria. The injection of ozone in thecontaminant removal system 100 may provide continuous removal of organicwastes and simultaneous disinfection of the liquid algae culture 110.Additionally, ozone may be applied at thresholds that may not harm theprimary algae type but may simultaneously remove contaminants, such asinvasive species of algae. Factors that may be responsible for theeffectiveness of the ozone treatment of the liquid algae culture 110 maycomprise the contact time of the ozone with the liquid algae culture110, the concentration of ozone, and/or the ozone demand of the water.In another embodiment, the ozone gas may be injected into the liquidalgae culture 110 in the vessel 105 prior to the liquid algae culture110 entering the pump 120 of the contaminant removal system 100.

In one embodiment, according to various aspects of the presentinvention, the contaminant removal system 100 may comprise one or moreadjustable operating parameters that may be optimized according to anynumber of factors, such as the growth requirements of the primary algaetype, the growth stage of the primary algae type, the zeta potential ofthe primary algae type, the size of the primary algae type, the pH ofthe liquid algae culture 110, the extent of coagulation of the algaecells in the liquid algae culture 110, the type of contaminants to beremoved from the liquid algae culture 110, the total organic carbon inthe liquid algae culture 110, the amount of algal biomass in the liquidalgae culture 110, the concentration of algal biomass in the liquidalgae culture 110, the salinity of the liquid algae culture 110 and thecontamination rate of the liquid algae culture 110.

In one embodiment, the adjustable operating parameters may be configuredsuch that the contaminant removal system 100 may remove between about0.1% to about 99.99% of the total contamination from the liquid algaeculture 110 by processing the total liquid algae culture 110 one time.In another embodiment, the adjustable operating parameters may beconfigured such that the contaminant removal system 100 may removebetween about 10% to about 99% of the total contamination from theliquid algae culture 110 by processing the total liquid algae culture110 one time. For example, the adjustable operating parameters may beconfigured such that the amount of remaining ash (dirt) in a harvestedculture or partial culture from an open algae growth system containsless than about 20% ash such as less than about 10% or less than about5% ash in the remaining biomass as measured by an ash-free dry weightcompared to the non-ash free dry weight.

In another embodiment, the height of the vertical chamber 130 may beselected to optimize the dwell time of the gas in the liquid algaeculture 110. The dwell time may be the average time that the liquidalgae culture 110 spends within the vertical chamber 130. In oneembodiment, the height of the vertical chamber 130 may range from 10 cmto 10 m. In another embodiment, the height of the vertical chamber 130may range from 0.1 m to 15 m.

In various embodiments, a flow rate of the liquid algae culture 110through the contaminant removal system 100 may be preselected. Thepreselected liquid flow rate of the liquid algae culture 110 may beadapted to aggregate the contaminants in the liquid algae culture 110.The flow rate of the liquid algae culture 110 may be controlled by thepump 120. In some embodiments, the preselected liquid flow rate of theliquid algae culture 110 may range from 1 Liters per minute (LPM) to1,000,000 LPM. The use of LPM throughout the specification and claimsmay be understood to encompass the use of both liters per minute andstandard liters per minute (SLPM). In another embodiment, thepreselected liquid flow rate of the liquid algae culture 110 may rangefrom 10 LPM to 10,000 LPM.

In various embodiments, a flow rate of the gas injected into the liquidalgae culture 110 by the pump 120 may be preselected. The preselectedgas flow rate may be adapted to aggregate the contaminants in the liquidalgae culture 110. For example, in some embodiments, the preselected gasflow rate may range from 1 LPM to 10,000,000 LPM. In one embodiment, thepreselected gas flow rate may range from 100 LPM to 100,000 LPM. In oneembodiment, the gas flow rate may range from 2.8 lpm (0.1 scfm) to2,800,000 lpm (100,000 scfm) for a process with a unit diameter lessthan 1 m where diameter is defined by the smallest dimension along anyaxis perpendicular to the direction of flow and may be maintained for atleast 20% of the flow length or at the smallest point of a conicalshape. Diameter may not describe the inclusion of a smaller connectingpipe. In another embodiment, the gas flow rate may range from 1 scfm to1000 scfm for an injection point within the skimmer unit with a unitdiameter less than 1 m where diameter is defined by the smallestdimension along any axis perpendicular to the direction of flow. Thediameter of the pipe may determine the gas velocity range and pressure.

In an exemplary embodiment of the present invention, the diameter of thevertical chamber 130 may be less than 1 m and the height of the verticalchamber may be less than 5 m. In this exemplary embodiment, the liquidflow rate may range from 1 LPM to 10000 LPM and the gas flow rate mayrange from 100 LPM to 100,000 LPM. In one embodiment, the liquid flowrate may range from about 30 LPM to about 500 LMP and the gas flow ratemay range from about 1,500 LPM to about 5,000 LPM.

In various embodiments of the present invention, the contaminant removalsystem 100 may support a continuous growth method or extended growthmethod for growing microalgae. For example, the contaminant removalsystem 100 may collect the foam 135 continuously for uninterruptedremoval of contaminants from the liquid algae culture 110. In oneembodiment, the continuous or extended growth method may provide animproved harvest yield of microalgae and may increase the growingefficiency of the microalgae culture by reducing the rate of death ofthe microalgae and reducing the materials and labor needed to start eachnew microalgae culture. Contaminant removal by the contaminant removalsystem 100 may achieve conditioning of the microalgae culture such thatthe microalgae may resume growth and/or grow to higher densities, whichmay increase production of each microalgae culture and may reduce costsassociated with lost algae cultures. In another embodiment, thecontaminant removal system 100 may remove contaminants at a rate whichallows the growth rate of the primary algae type in the vessel 105 tomaintain a constant algae culture density.

In an exemplary embodiment, the contaminant removal system 100 may atleast partially reduce contaminant particles in the liquid algae culture110 comprising a culture of Nannochloropsis, product-excretingcyanobacteria, and/or any other microalgae leaving the culturesubstantially unharmed. For example, the liquid algae culture 110exiting the vertical chamber 130 of the contaminant removal system 100when run continuously for 3 days may contain unharmed Nannochloropsismicroalgae and a reduced concentration of contaminants. TheNannochloropsis microalgae cells exiting the contaminant removal system100 may exhibit cellular characteristics of being the younger, round,and healthier individual algae cells found in the liquid algae culture110 that entered the contaminant removal system 100. The contaminantsremoved from the liquid algae culture 110 and found in the collectioncontainer 140 may comprise older, dead, and/or coagulatedNannochloropsis microalgae as well as large concentrations of non-algaecontaminants measuring approximately 50 microns or less. The microalgaecells in the liquid algae culture 110 exiting the contaminant removalsystem 100 may continue to grow when placed in a separate tank andmonitored for five days. Accordingly, the majority of a culture ofNannochloropsis microalgae may successfully travel through thecontaminant removal system 100 and may return to the vessel 105 forfurther culturing, wherein the algae cells of the primary algae type areconsidered to be in a healthy state with the liquid algae culture 110having a reduced concentration of contaminants.

Example 1

The effect of treating the liquid algae culture 110 with the contaminantremoval system 100 was tested on an algae culture primarily comprisingNannochloropsis microalgae grown in a 4.57-m long V-trough reactor (140degree angle) with algae convection achieved through the use of a 1.5 hpcentrifugal pump 340 lpm to rotate the fluid in a clockwise fashion. Thereactor width is 1.5 m and the maximum depth at the apex of the centralangle is 0.46 m. The liquid volume in the reactor was 1,580 liters(about 427 gallons). The contaminant removal system 100 was run for 12hours (throughout the night). The Nannochloropsis cells run through thecontaminant removal system 100 remained viable after the contaminantremoval process and continued to grow in the following days. The cleaneffluent was sent back to the vessel 105 for continued growth andrecycling through the contaminant removal system 100.

The contaminant removal system 100 used in FIG. 7 was a conventionalcommercially available aquarium protein skimmer adapted for use as acontaminant removal system 100 wherein the protein skimmer has an inlettube, a pump, a vertical chamber, a collection container, and an outlettube. Specifically, the contaminant removal system 100 was Aqua-Cskimmer EV 2000 from AquaC (referred to as “AquaC”) is 101.6 cm (40″)tall and has a footprint of 22.86 cm×30.48 (9″×12″). There is a 1.54 cm(1″) hose barb for the water input and a 5.08 cm (2″) gate valve thatcontrols the flow through the AquaC. The gate valve is 22.86 cm (9″)above the bottom of the AquaC. The barb size on the collection cup is1,905 cm (¾″). The AquaC contains dual threaded air inlets 0.9525 cm(⅜″) with 0.635 cm (¼″) fittings. The Aqua-C is rated by themanufacturer for 1,892 liters (500 gallon)-7.570 liters (2,000 gallon)reef tanks. The water pump drives the liquid algae culture through theAquaC at 1,570 lph (2000 gallon per hour) is connected to the skimmervia a 1.54 cm) (about 0.6″) flex tube. In one embodiment, the 0.635 cm(¼″) air nozzle was configured to be 100% opened during operation. Thedual 0.635 cm (¼″) air inlets were fully open with approximately 15 Lpmof air for each for a total of 30 Lpm of air. The rotameter thatcontrolled the gas velocity into the AquaC and the pump that fed theAquaC unit were modified such that the rotameter was increased to allowfor a higher gas velocity into the AquaC. The pump was a faster flowrate than disclosed by the manufacturer. The inlet pipe diameter forfeeding the AquaC water was also modified to a smaller diameter. The airinjection port on the skimmer was be set to maximum air injection tocreate a desired amount of foam fractionation.

The AquaC removed approximately 24% ash (30% average prior toprocessing, and 6% average ash after processing as determined by a dryweight and ash free dry weight measurement) and removed 16.19% of theNannochloropsis cells from the culture. It is anticipated fromexperiments that the AquaC may remove between 1 and 25% of the livingalgae cells from a culture over a 12 hour period when the incoming flowof feed to the AquaC is between about 10-1,000 turnovers per day. Theamount of overhead solids removed was 57 liters (10-15 gallons).

The vessel 105 had a volume of about 1,580 liters (427 gallons). TheAquaC purified the liquid algae culture 110 in the vessel 105 for 12hours throughout the night. The turnover time was approximately 4.79turnovers per hour. The total number of turnovers during the 12 hourperiod was 58 times.

FIG. 7 shows the dry weight (DW) of a sample of the liquid algae culture110 harvested at various time points. At each data point, three 200 mLsamples of the liquid algae culture 110 were removed from the vessel105, centrifuged to pellet the solid material, dried, and weighed. Theaverage weight of the triplicate samples provides each data point. Anadditional step of washing the solid material to remove the ash wasperformed to obtain the data points for the ash free dry weight (AFDW).FIG. 7 shows that the AquaC was applied to the liquid algae culture 110after 24 hours. The DW of the liquid algae culture 110 was initiallyapproximately 1.0 g/L and the AFDW of the liquid algae culture 110 wasapproximately 0.79 g/L. This indicates that approximately 21% of the DWof the liquid algae culture 110 was ash. After the AquaC was applied tothe liquid algae culture 110, the ash was reduced to approximately 5-8%of the DW of the liquid algae culture 110. Further, the Nannochloropsiscells run through the AquaC remained viable after processing andcontinued to grow in the following 5 days. The AquaC removedapproximately 16.19% of the Nannochloropsis cells from the liquid algaeculture 110. The amount of solids removed from the liquid algae culture110 over the 144 hour trial was about 57 L (10-15 gallons).

Prior to processing by the AquaC, the culture showed TEP clumps,diatoms, and competitors to the Nannochloropsis microalgae such asunwanted cyanobacteria as observed under a microscope (100×magnification) (not shown). After processing by the AquaC there were aminimal number of clumps and diatoms observed (>90% reduction inoccurrence). Accordingly, the AquaC removed non-viable cells, dirt andparticulate matter, clumped cells, predators, competitors and otheralgal species that are larger than Nannochloropsis 202-3, which has asize range of 2-6 um.

Example 2

In another trial use of the Aqua-C skimmer EV 2000, the AquaC wasmodified by installing a 2000 gph pump to operate with a liquid flowrate of 7,570 liters per hour. The air nozzle was run 100% open 0.635 cm(¼″ diameter) with a gas flow rate of approximately 20-30 lpm. The AquaCwas utilized for 12 hours overnight on a second vessel 105 (15′V-Trough) which was similar to that described in FIG. 7 except the pumphorsepower (hp) was operated at a third power (0.5 hp), resulting in alower circulation velocity. The AquaC was used with a 7,570 liters perhour (2000 gph) pump. The reactor had a volume of 1,580 liters (427gallons). Accordingly, the turnover rate of the liquid algae culture 110through the AquaC is approximately 12.5 minutes, wherein the totalvolume of the liquid algae culture 110 would flow through the processonce every 12.5 minutes and would spend approximately 0.25 minutes(dwell time) in the AquaC. Over a 12 hour period, there was an averageof about 58 iterations of liquid algae culture 110 into the AquaC. Thedwell time was the average residence time that the liquid algae culture110 spent within the internal volume of the AquaC. The AquaC internalvolume is divided by the volumetric flow rate of the incoming liquidalgae culture 110 to define an average residence time, therein describedas the dwell time.

The gate valve on the return to the vessel 105 was kept 50% open for theduration of the run to create backpressure to promote the foamfractionation of the liquid algae culture 110. The backpressure (adjuststhe dwell time in the Aqua-C) is adjusted according to the air injectionrate and turnover rate. The dual 0.635-cm (¼″) air inlets were fullyopen with approximately 15 Lpm of air for each for a total of 30 Lpm ofair. The air injection port on the Aqua-C is set to maximum airinjection to create the desired foam fractionation, thus the airinjection ports are wide open. The Aqua-C ran overnight (12 hours) andapproximately 5 gallons of overhead solids were collected. Thecollection appeared to be deep green foam as opposed to the brown sandcolored foam observed as described in example 1.

The level of contamination from this vessel 105 was reduced to a levelfor viable cell culture and algal growth resulting in a reduced amountof overhead solids removed. The use of the Aqua-C reduced the amount ofcompetitors, diatoms, and TEP by more than half as measured bymicroscope with 100× magnification (not shown). Contamination may bepresent in all cultures that are open to the external environment. Thereare levels that may be tolerable for algae production however the growthrate and population dynamics of the contaminant can quickly surpasslevels for viable algae culture. The Aqua-C may reduce the contaminationto levels that are tolerable for algae production in the vessel 105. Thereactor exhibited a 1.4% reduction in ash content in the dry weightafter processing by the Aqua-C. This indicated the removal of totalsuspended solids (TSS) via the Aqua-C. The reduction of TSS can increaselight distribution within the photobioreactor (less light blocking bysolids) as well as remove particles that would lead to explosions ofcontamination populations. The 5-day average of algae growth, afterprocessing by the Aqua-C, increased by approximately 10% from 0.141gram/Liter-Day (g/L-D) to 0.157 g/L-D.

Example 3

In yet another trial use of the Aqua-C EV 2000, and referring to FIGS. 8and 9, the Aqua-C was modified to operate with a liquid flow rate of7,570 liters per hour (2000 gph), the flow rate of air was 20-30 lpm,the volume of the vessel was 114 liters (about 30 gallons). The liquidalgae culture 110 was taken from an outdoor contaminated culture andplaced into a separate treatment container for processing by the Aqua-C.The Aqua-C was operated for 6 hours resulting in 324 turnovers throughthe Aqua-C. The Aqua-C was operated with a liquid flow rate of 7,570liters per hour (about 2050 gph) and the air injection port was run 100%open 0.635 cm (¼″ diameter) with a gas flow rate of approximately 20-30lpm.

FIG. 8A shows a microscopy picture of the liquid algae culture 110effluent after leaving the skimmer and returning to the vessel 110. Thisimage shows healthy Nannochloropsis cells. FIG. 8B shows thecontaminants removed from the liquid algae culture 110 by the Aqua-Cincluding unwanted cyanobacteria. The Aqua-C effluent was analyzed forthe presence of unwanted cyanobacteria after the treatment and nounwanted cyanobacteria were found. The algal culture was then inoculatedinto a new vessel 105 and continued to grow (0.2-0.3 g/L day) (see FIG.9). The culture was not growing and dying off prior to the applicationof the Aqua-C.

Example 4

In yet another trial use of the Aqua-C skimmer EV 2000, the Aqua-C wasconfigured to have a liquid flow rate of 7570 lph, a liquid algaeculture 110 dwell time of 0.25 minutes, a gas injection rate of 20-30lpm, a turnover rate of 12.5 minutes, and a total of 324 turnovers ofthe liquid algae culture 110. The Aqua-C removed contamination such asTEPs, bacteria, ciliates, unwanted cyanobacteria and other larger >30 umsolids which may include competing algal species and clumped unhealthyalgal cells without removing significant amounts of Nannochloropsismicroalgae (less than 25% of the healthy cells may be sacrificed toretain a healthy liquid algae culture 110 that is viable for continuedgrowth).

Referring to FIG. 10, the skimmer was tested on an indoor vessel 105without the presence of weather-induced solids accumulation as in theconditions of FIGS. 7-9 (e.g. blowing dirt). The vessel 105 had a volumeof 1,580 liters (427 gallons) and was a 15′ V-Trough reactor with a 140degree V shaped bottom that is 5.5° (1.68-m) wide by 15′ (4.57 n) longand filled 20 cm from the top giving a volume of about 1,580 liters. Thegrowth rates of the liquid algae culture 110 was (0.03 g/L day; 9 g/m²day) prior to skimming and decreased in productivity due tocontamination and fouling. The growth rate of the liquid algae culture110 increased to 0.04 g/L day; 12 g/m²-day after skimming for 6 hours.The liquid algae culture 110 was grown indoors under 24 hour fluorescentlighting, which may illustrate a benefit of using the contaminantremoval system 100 both inside and outside.

Example 5

In another trial of the Aqua-C skimmer EV 2000, the Aqua-C wasconfigured to have a liquid flow rate of 7570 lph, a liquid algaeculture 110 dwell time of 0.25 minutes, a gas injection rate of 20-30lpm, a turnover rate of 12.5 minutes. However, the total number ofturnovers of the liquid algae culture 110 was 57.6. The Aqua-C wascoupled to a 15′ (4.57 m) 140 degree V-Trough vessel 105 with a 0.5 HPcentrifugal pump for mixing. The vessel 105 has a 140 degree V bottomand is 5.5° (1.68-m) wide by 15′ (4.57 m) long and is filled up to 20 cmfrom the top giving a volume of 1,580 L. The liquid algae culture 110 ofNannochloropsis microalgae was grown for over 7 days without harvestingsince inoculation.

The Aqua-C was utilized for 12 hours overnight on with the running 0.5HP centrifugal pump. The gate valve on the return to the trough was kept50% open for the duration of the run. The dual ¼″ air inlets were fullyopen with approximately 15 lpm of air for each for a total of 30 lpm ofair. Approximately 5 gallons of material was collected from thecollection container 140 of the Aqua-C. The material in the collectioncontainer 140 appeared to be a deep green foam as opposed to the brownsand colored foam observed in another trial. Observations indicated thatprocessing by the Aqua-C reduced the number of competitors and diatomcount. TEP was slightly elevated the day after processing but decreaseddirectly thereafter and therefore may have been a result of processingby the Aqua-C. Taking 5-day averages of growth, after skimming thegrowth in the vessel 105 increased from 0.141 g/L-D to 0.157 g/L-D for a10% increase.

Example 6

In another trial of the Aqua-C skimmer EV 2000, ozone gas mixed with airwas applied to the liquid algae culture 110 in the vessel 105 directlythrough an air sparger in the vessel 105 or to the air nozzle in theprocessing by the Aqua-C to provide ozone gas at a concentration ofbetween about 0.01 mg/L to 1.0 mg/L of liquid algae culture 110. Theozone gas was applied to the processing by the Aqua-C to increase theculture viability by applying the ozone in the gas/water interface ofthe processing by the Aqua-C as opposed to directly in the algaeculture, for sterilizing and/or killing the contaminants in the liquidalgae culture 110. In each of four runs of this trial, a dying(crashing) liquid algae culture 110 was returned to a growth phase, thusincreasing the longevity of the culture, and contaminants were removed.

In a first run of the trial, the contaminated liquid algae culture 110was disposed in a vessel 105 comprising a Tri-V Trough with 100 degreeangles. The ozone gas was directly applied to the liquid algae culture110 in the vessel 105 through the air sparger for 15 minutes followed by20 minutes of processing by the Aqua-C. The air pressure was 80 psi andthe air injection rate into the ozone unit was 850 lpm at a level of 20%ozone injection. The ozone gas was injected into an airline of thevessel 105 at a flow rate of 42 lph (0.7 lpm). After the ozonetreatment, the vessel 105 was processed by the Aqua-C. The rate of gasinjection was approximately 15 lpm with 20% ozone. The concentration ofmicroalgae in the vessel 105 was 0.49 g/L prior to processing by theAqua-C and ozone treatment. The concentration of microalgae in thevessel 105 was 0.41 g/L after processing by the Aqua-C and ozonetreatment. The ozone and Aqua-C treatment removed a fraction of thepredators and competitors.

The configuration of the injection of ozone into the vessel 105 were 1%Ozone=12.8 g/m³ Ozone in air, 100 g O3/m³=7.8% O₃ in air, % Ozoneinjection into air: 20% Ozone=256 g/m³ Ozone, Air injection: 42 lph or0.7 lpm, Application Rate: 0.1792 grams per minute, Application Time: 15minutes, and Total Ozone Applied: 2.688 grams of ozone. Theconfiguration of the Aqua-C was a flow rate of 7570 lph, a dwell time of0.25 min, gas injection of 15 lpm, turnover rate 1.51 min, and a totalturnover of about 20 minutes for 45.3 turnovers with a total of 2.688grams of ozone applied to the liquid algae culture 110. The Aqua-C wasrun under the described conditions for 20 minutes. Nutrients (190 mL ofnutrients) were added to the vessel 105. The vessel 105 was harvested.Prior to harvest, the bottom of the vessel 105 was brushed and agitationwas turned off so the clumps of solid material would settle at thebottom of each vessel 105 where 18.9 L was harvested.

In a second run of the trial applying ozone gas separately to the liquidalgae culture 105 from the Aqua-C, the ozone gas was applied to the airsparger of the vessel 105. The liquid algae culture was maintained forabout 264 hours. The configuration of the injection of ozone into thevessel 105 was: 1% Ozone=12.8 g/m³ Ozone in air, 100 g O3/m³=7.8% O₃ inair, compressed air=80 psi, ozone rotameter=850 lpm, 50% ozone mixedwith 50% air (640 g/m³ Ozone), air injection: 42 lph or 0.7 lpm,application rate: 0.448 grams per minute, application time: 15 minutes,total ozone applied: 6.72 grams of ozone, and the vessel was treatedwith ozone for 20 min. The Aqua-C was applied to the vessel 105 for 30min. The configuration of the Aqua-C was flow rate: 7570 lph, dwelltime: 0.25 min, gas injection: 15 lpm, Turnover rate: 1.51 min, TotalTurnovers per treatment: 45.3 turnovers (with a total of 8.96 grams ofozone applied).

In a third run of the trial applying ozone gas separately to the liquidalgae culture 105 from the Aqua-C, the ozone gas was applied to the airsparger of the vessel 105. The liquid algae culture was maintained forabout 336 hours. The configuration of the injection of ozone into thevessel 105 was: compressed air=80 psi, ozone rotameter=850 lpm, 50%ozone mixed with 50% air (640 g/m³ Ozone), 1% Ozone=12.8 g/m³ Ozone inair, 100 g O3/m³=7.8% O₃ in air, air injection: 42 lph or 0.7 lpm,Application Rate: 0.448 grams per minute, Application Time: 10 minutes,Total Ozone Applied: 4.8 grams of ozone, and vessel 105 was treated withozone for 10 min. The Aqua-C was placed on the vessel 105 after ozonetreatment for min. The configuration of the Aqua-C was flow rate: 7570lph, Dwell Time: 0.25 min, Gas Injection: 15 lpm, Turnover rate: 1.51min, Total Turnovers per treatment: 45.3 turnovers (with a total of 0.5grams of ozone applied).

In a fourth run of the trial, ozone gas was applied to the air nozzle ofthe Aqua-C. The liquid algae culture 110 was maintained for about 384hours. The configuration of the injection of ozone into the Aqua-C was:compressed air=80 psi, ozone rotameter=850 lpm, 50% ozone mixed with 50%air (640 g/m³ Ozone), 1% Ozone=12.8 g/m³ Ozone in air, 100 g O3/m³=7.8%O₃ in air, air injection flowrate: 15 lpm, application rate: 9.6 gramsper minute, total ozone applied: 192 grams of ozone, and the applicationtime of the Aqua-C and ozone treatment was 20 minutes. The configurationof the Aqua-C was flow rate: 7570 lph, dwell time: 0.25 min, gasinjection: 15 lpm, turnover rate: 1.51 min, total turnovers pertreatment: 30.2 turnovers (with a total of 192 grams of ozone applied).

Referring to FIG. 12, a graph of the dry weight and ash free dry weightof the liquid algae culture 110 of the fourth run of this trial is shownover 384 hours. The liquid algae culture 110 was crashing prior totreatment with the ozone and the Aqua-C. After the treatment, the growthof the liquid algae culture 110 trended upwards.

Example 7

Referring to FIG. 11, the effect of treating a liquid algae culture 110with the contaminant removal system 100 was tested using a commerciallyavailable protein skimmer with air venture injection. This commerciallyavailable protein skimmer was model RK 10AC-PF from RK-2 Systems(referred to as “RK-2”) and is 215.9 cm (85″) tall and has a footprintof 38.10 cm×91.44 cm (15″×36″). There is a 1.54 cm (about 0.6″) hosebarb water input and a 5.08 cm (about 2″) gate valve that controls flowthough the RK-2. The gate valve is 35.56 cm (14″) above the bottom ofthe RK-2. The RK-2 is rated by the manufacturer for up to 3785.44 L(about 1000 gallon) reef tanks. The volume of the vertical chamber 130was 71 L. The venturi water pump drives the liquid algae culture 110through the skimmer at 20,439 lph (5315 gallon per hour) and isconnected to the RK-2 via a 1.54 cm (about 0.6″) flex tube. The 0.635 cm(¼″) air nozzle was configured to be 100% opened during operation. Thedual 0.635 cm (¼″) air inlets were fully open with approximately 107 Lpm(6435 lph) of air. The gas flow rate was greater than 50 scfm. The airinjection port on the skimmer was set to maximum air injection to createa desired amount of foam fractionation.

The RK-2 was coupled to four 4′×4′ photobioreactors (vessels 105). Thetotal volume of the liquid algae culture 110 was 368 L. The dwell timeof the liquid algae culture 110 in the vertical chamber 130 was 40.3seconds with approximately 3.44 min turnover rate. The total number ofturnovers of the liquid algae culture 110 was approximately 1,256 inthree days.

Nannochloropsis microalgae were grown in a 121.92 cm×121.92 cm (4′×4′)46 liter flat panel photobioreactor (vessel 105) until the culture wascontaminated and clumping. The contaminated algae was added to theculture and diluted 50% with fresh salt water (30 g/l). The culture rancontinuously through the skimmer for three days. Samples from the vessel105 and skimmer collection container 140 were taken on day 3. The vessel105 contains the liquid algae culture 120 that has been run through theskimmer and the collection container 140 contains the contaminantsremoved by the protein skimmer from the liquid algae culture 110. FIG.12A shows a 100× magnification microscopy picture of the liquid algaeculture 110 sampled from the vessel 105 that has been cleaned with theprotein skimmer with air venturi injection. The cells in FIG. 11A areNannochloropsis microalgae cells with no observed signs of contaminantsas the contaminants were non detectable. As a result, theNannochloropsis microalgae cells shown in FIG. 11A may have an increasedsurface area for gas exchange, receiving light, and nutrientconsumptions as compared to the coagulated and contaminated cells shownin FIGS. 11B and 11C.

FIG. 11B shows a 100× magnification microscopy picture of the liquidalgae culture 110 that was collected from the top portion of thematerial collected in the RK-2 collection container 140. FIG. 11B showncontaminants such as solids, coagulated microalgae cells, and unwantedcyanobacteria. FIG. 11C shows a 100× magnification microscopy picture ofthe liquid algae culture 110 that was collected from the bottom portionof the material collected in the RK-2 collection container 140 thatcomprises a dense sediment. This material also contains contaminantssuch as solids, coagulated microalgae cells, and unwanted cyanobacteria.

Example 8

In another trial use of the model RK10AC-PF from RK-2 Systems,Nannochloropsis microalgae were grown in a 121.92 cm×121.92 cm (4′×4′)46 liter flat panel photobioreactor (total volume 184 L) until theculture was contaminated. The liquid algae culture 110 was removed andplaced into a 184 L vessel 105 with aeration for agitation. The dual0.635 cm (¼″) air inlets were fully open with approximately 107 Lpm(6434.5 lph) of air. The venturi water pump drives the liquid algaeculture 110 through the RK-2 at 20,439 Lph (5315 gallon per hour). Thevolume of the vertical chamber 130 was 72.1 L. The dwell time of theliquid algae culture 110 in the vertical chamber 130 was 40.3 secondswith approximately 1.7 min turnover rate. There total number ofturnovers of the liquid algae culture 110 was approximately 60.7 in 60minutes.

Particles in the liquid algae culture 110 were initially about 20%contamination and 80% Nannochloropsis microalgae. After approximately 60minutes of RK-2 use where the liquid algae culture 110 passed throughthe RK-2 approximately 60.7 times, the contamination was reduced by 6%to be 14% of the total particles. Contamination was considered to becells outside the size range of Nannochloropsis (2-8 um).

An automated FlowCAM® instrument for particle size analysis by digitalimaging of particles in a continuous flow of fluid was set considerparticles that were 2-8 microns in diameter to be “normal.” The FlowCAM®instrument considered all particles outside this range to becontamination and yielded a contamination level of 14% of the totalparticles. As in the microscopy pictures of Example 6, after running theliquid algae culture 110 through the skimmer for 60 minutes, a sample ofthe liquid algae culture 110 from the vessel 105 showed theNannochloropsis microalgae cells with no signs of contaminants (notshown). The microscopy pictures of the liquid algae culture 110 thatwere collected from the RK-2 collection container 140 showed solids,coagulated microalgae cells, and unwanted cyanobacteria (not shown).

In one embodiment, according to various aspects of the presentinvention, the contaminant removal system 100 may be used with a liquidalgae culture 110 comprising salt-water. Use of the contaminant removalsystem 100 in salt-water applications may remove organic compounds fromthe liquid algae culture 110 before the organic compounds decomposedinto waste. In some embodiments, removal of the organic compounds mayimprove the redox potential of the liquid algae culture 110. The redoxpotential of the liquid algae culture 110 may regulate a variety ofbiogeochemical reactions, such as surface charges between elements, andmay characterize oxidation-reduction status of surface environments. Theredox potential may be determined by measuring the electrochemicalpotential within the water of the liquid algae culture 110.

In various embodiments, the contaminant removal system 100 may be usedwith two or more, two to ten, or two to one hundred or more parallelalgae growth systems, whereas interconnecting pipes, valves, andcontrols are used to intermittently switch flow between vessel 105 suchthat multiple growth systems may be cleaned by each contaminant removalsystem 100 to reduce the number of units required.

Various implementations of the present invention may be used inconjunction with other devices to promote the purification of the liquidalgae culture 110 and/or promote the growth of the primary algae type.In some embodiments, the contaminant removal system 100 may be used witha series of devices in fluid communication which apply different methodsof contaminant removal and treatment of the liquid algae culture 110.Disclosed below are a number of exemplary, non-limiting embodiments thatmay include the contaminant removal system 100 configured for removingcontaminants from the liquid algae culture 110. The embodiments of thecontaminant removal system 100 described are intended to encompassalternative arrangements of the components of the contaminant removalsystem 100 in a different order, and/or removal of one or more of thecomponents of the contaminant removal system 100 in which the resultingsystem would still achieve results substantially similar to the resultsof the disclosed examples.

In various embodiments of the present invention, the return path to thevessel 105 may be coupled to a return pipe 150 to carry the liquid algaeculture 110 back to the vessel 105 from the contaminant removal system100 and/or to another device for additional filtering, harvesting and/orother processing. In an exemplary embodiment, the return pipe 150 mayinclude a light source disposed along the length of the return pipe 150that may expose the algae in the liquid algae culture 110 returning tothe vessel 105 (or another device) to Photosynthetically ActiveRadiation (PAR) during its return to the vessel 105. The light sourcemay comprise, but is not limited to, a plurality of light emittingdiodes (LED). The return pipe 150 may also include a gas injector, orother device for introducing a gas into the liquid algae culture 110, tointroduce a gas such as air, carbon dioxide, or ozone into the liquidalgae culture 110 during its return to the vessel 105.

In one embodiment, the return pipe 150 may carry the liquid algaeculture 110 to a device for harvesting the microalgae. For example, thereturn pipe 150 may be coupled to a harvesting device such as acentrifuge that uses gravitational force to separate the growth mediafrom the microalgae and/or the product-excreting cyanobacteria in theliquid algae culture 110. In one embodiment, the harvesting device maybe an electric dewatering drum filter and/or other device(s) forseparating the microalgae and/or product-excreting cyanobacteria fromthe growth medium. In one embodiment, the separated microalgae may bereturned to a vessel 105 for continued growth. For example, a culture ofproduct-excreting cyanobacteria may experience negative effects from theaccumulation of carbon compounds and/or chemicals in the growth medium.The isolated product-excreting cyanobacteria may continue to grow whenadded to fresh growth media or an existing liquid algae culture 110. Insome embodiments the isolated microalgae and/or product-excretingcyanobacteria may be further processed to obtain a target product, suchas a phytochemical, chemical, lipid, oil, hydrocarbon, and/or a biofuel.In another embodiment, the growth medium that is separated from themicroalgae may be further processed to isolate compounds that have beenexcreted from the microalgae. For example, the growth medium removedfrom the harvesting device, such as the centrifuge, may be furtherpurified to isolate a product excreted by the product-excretingcyanobacteria.

In various embodiments of the present invention, the contaminant removalsystem 100 may be coupled to one or more sensors and control systemsthat may be employed as an automated control system to control the flowrate of the liquid algae culture 110 entering the contaminant removalsystem 100, the flow rate or velocity of the gas injected into theliquid algae culture 110, the type of gas to inject into the liquidalgae culture 110, and/or the rate of contaminant removal from thecollection container 140.

In some embodiments, according to various aspects of the presentinvention, methods and devices of contaminant removal and fluidtreatment that may be used in combination with the contaminant removalsystem 100 may comprise, but is not limited to: a device configured tointroduce coagulants and flocculent into the liquid algae culture 110which may cause coagulated algae or flocs of algae to form in the liquidalgae culture 110 for more efficient removal from water; manipulation ofpH to increase or reduce cell clumping; a mechanical filtering devicecomprising a membrane or media with apertures for allowing onlyparticles of a certain size within the liquid algae culture 110 to passthrough the filter; an electric dewatering device comprising chargedelectrodes which apply an electrical field to a solution to inducemovement of water away from solid particles in the liquid algae culture110 by electrical attraction; an ultra violet (UV) light sterilizercomprising a device providing light of a specific wavelength whichbreaks down organisms by exposure; an activated carbon filter comprisingporous carbon for allowing only particles of a certain size and typewithin the liquid algae culture 110 to pass through the porous carbon;and a centrifuge configured to apply acceleration to separate matterwithin the liquid algae culture 110 based on density of the matter.

Referring to FIG. 2, in an exemplary embodiment of the present invention200, the contaminant removal system 100 may be implemented inconjunction with the vessel 105, a device for introducing coagulants andflocculent 205 into the liquid algae culture 110, a UV sterilizer 210,and an activated carbon filter 215. The vessel 105 may be coupled to thecoagulant and flocculent device 205 such that the liquid algae culture110 may flow from the vessel 105 through the coagulant and flocculentdevice 205. The contaminant removal system 100 may be configured toreceive liquid algae culture 110 from the coagulant and flocculentdevice 205 and may allow for removal of a portion of the liquid algaeculture 110 or algae for harvest. The coagulant and flocculent device205 may at least one of introduce chemicals (flocculating agents) thatmay contain cationic and/or anionic particles that may cause contaminantparticle to clump together for easy separation from the liquid algaeculture 110. The coagulant and flocculent device 205 may also providerapid mixing of the liquid algae culture 110 to promote the formation ofthe clumps.

The UV sterilizer 210 may be configured to receive at least a portion ofthe liquid algae culture 110 from the contaminant removal system 100 toexpose the liquid algae culture 110 to UV radiation. The activatedcarbon filter may be configured to receive the liquid algae culture 110that was exposed to UV radiation from the UV sterilizer 210. Theactivated carbon filter 215 may fluidly connect to the vessel 105 forreturn of the liquid algae culture 110 to the vessel 105 for continuedgrowth of the algae culture and/or for harvesting purposes.

Referring to FIG. 3, in another exemplary embodiment of the presentinvention 300, the contaminant removal system 100 may be implemented inconjunction with the vessel 105, an electric dewatering drum filter 305,the UV sterilizer 210, and the activated carbon filter 215. The electricdewatering drum filter 305 may be configured to receive the liquid algaeculture 110 from the vessel 105. The contaminant removal system 100 maybe configured to receive at least partially purified liquid algaeculture 110 from the electric dewatering drum filter 305 and may allowfor removal of a portion of the liquid algae culture 110 or the algaefor harvest. The UV sterilizer 210 may be configured to receive at leasta portion of the liquid algae culture 110 from the contaminant removalsystem 100 to expose the liquid algae culture 110 to UV radiation. Theactivated carbon filter 215 may be configured to receive the liquidalgae culture 110 that was exposed to UV radiation from the UVsterilizer 210. The activated carbon filter 215 may fluidly connect tothe vessel 105 for return of the liquid algae culture 110 to the vessel105 for continued growth of the algae culture and/or for harvestingpurposes.

Referring to FIG. 4, in yet another exemplary embodiment of the presentinvention 400, the contaminant removal system 100 may be implemented inconjunction with the vessel 105, a mechanical filtration device 405, acentrifuge 410, the UV sterilizer 210, and the activated carbon filter215. The contaminant removal system 100 may be configured to receive theliquid algae culture 110 from the vessel 105. The mechanical filtrationdevice 405 may be configured to receive the liquid algae culture 110from the contaminant removal system 100. The centrifuge 410 may beconfigured to receive a portion of the liquid algae culture 110 from themechanical filtration device 405 and allow for removal of a portion ofliquid algae culture 110 or the algae for harvest. The UN sterilizer 210may be configured to receive at least a portion of the liquid algaeculture 110 from both the mechanical filtration device 405 and thecentrifuge 410. The activated carbon filter 215 may be configured toreceive liquid algae culture 110 that was exposed to UV radiation fromthe UV sterilizer 210. The activated carbon filter 215 may fluidlyconnect to the vessel 105 for return of the liquid algae culture 110 tothe vessel 105 for continued growth of the algae culture and/or forharvesting purposes.

Referring to FIG. 5, in yet another exemplary embodiment of the presentinvention 500, the contaminant removal system 100 may be implemented inconjunction with the vessel 105, the mechanical filtration device 405,the centrifuge 410, the UV sterilizer 210, and the activated carbonfilter 215. The mechanical filtration device 405 may be configured toreceive the liquid algae culture 110 from the vessel 105. The centrifuge410 may be configured to receive a portion of the liquid algae culture110 from the mechanical filtration device 405 and allow for removal of aportion of algae for harvest. The contaminant removal system 100 may beconfigured to receive the liquid algae culture 110 from the mechanicalfiltration apparatus 405 and/or the centrifuge 410. The UV sterilizer210 may be configured to receive at least a portion of the liquid algaeculture 110 from the contamination removal system 100. The activatedcarbon filter 215 may be configured to receive the liquid algae culture110 that was exposed to UV radiation from the UV sterilizer 210. Theactivated carbon filter 215 may fluidly connect to the vessel 105 forreturn of the liquid algae culture 110 to the vessel 105 for continuedgrowth of the algae culture and/or for harvesting purposes.

FIG. 6 representatively illustrates an exemplary method of operation ofa contaminant removal system 100 according to various aspects of thepresent invention (600). The operation of the contaminant removal system100 may comprise coupling the inlet tube 115 to the vessel 105 such thatthe inlet may be in contact with the liquid algae culture 110 (605). Thecontaminant removal system 100 may receive the liquid algae culture 110from the vessel 105 into the inlet tube 115 (610). The contaminantremoval system 100 may pump the liquid algae culture 110 from the inlettube 115 to the pump 120 using the preselected flow rate. Thecontaminant removal system 100 may inject a gas into the liquid algaeculture 110 using the preselected gas flow rate mix the gas with theliquid algae culture 110 to create gas bubbles (615), mix the gasbubbles and the liquid algae culture 110 to create the gas and liquidculture mixture 125 (620). The gas and liquid culture mixture 125 may bereceived into the first end of the vertical chamber 130 and generate thefoam 135 comprising the contaminants. The foam 135 may travel from thefirst end to the second end of the vertical chamber 130. The foam 135may be collected in the collection container 140 (625), wherein theseparation and collection of the foam from the gas and liquid culturemixture may improve the growth rate of the microalgae and/or thecyanobacteria. The foam 135 comprising the contaminants may be removedfrom the liquid algae culture 110, while retaining at least 80% of theprimary algae type in the liquid algae culture 110 (630). The purifiedliquid algae culture 110 may be returned to the vessel 105 through theoutlet tube 145 and/or the return pipe 150 for continued growth of theprimary algae type and/or for harvesting purposes (635).

The contaminant removal system disclosed above may be used in anexemplary method disclosed herein for removing contaminating substancesfrom a fluid comprising an algae culture and growth medium. The methodmay comprise a contaminant removal system receiving fluid from a vesselconfigured for growing a primary algae type in an aquaculture forharvesting purposes, removing contaminating substances from the fluidwith the components of the contaminant removal system while retaining atleast 80% of the primary algae type in the fluid, and returning thefluid exiting the contaminant removal system to the algae culturingvessel. The contaminant removal system may comprise at least thecontaminant removal system 100 disclosed above, and may further compriseany of the systems or system components disclosed above to removecontaminating substances from the fluid. The method may further comprisethe additional step of removing a portion of the fluid or algae from acomponent of the contaminant removal system for algae harvest. Themethod may also further comprise the additional step of controllingaspects of the contaminant removal system including the flow rate offluid into the contaminant removal system, the rate of gas injection,the type of gas injected, and the rate of contaminant removal, throughan automated sensors and controls system.

As disclosed above with the contaminant removal systems, the method maytreat any portion of the fluid from the algae culturing vessel toachieve the desired level of contaminant removal, including treating upto 100% of the fluid from the algae culturing vessel. In someembodiments, the method may further comprise the step of treating thefluid with a wash, such as, but not limited to fresh water, solvent, ora pre-treatment solution to prepare the fluid or algae for a subsequentprocess such as, but not limited to, extraction and/or harvest.

In one exemplary embodiment of a method for removing contaminatingsubstances, Nannochloropsis microalgae may be grown in a saltwatermedium within a V-trough growing vessel. A portion of the algae culturecontaining fluid may flow or be pumped from the V-Trough to acontaminant removal system, wherein the fluid may be mixed with aninjected gas, such as air, carbon dioxide, or ozone at approximately1-50 scfm. The fluid and gas mixture may be transferred into a verticalwater chamber where the gas bubbles and particles adsorbed to the gasbubbles may rise to the top of the vertical water chamber and create afoam rich in contaminants from the fluid. The fluid may flow through thecontaminant removal system at approximately 1-45 gpm. The foam maycollect in a collection tote and may be removed from the contaminantremoval system. The remaining fluid containing 80% or more of theNannochloropsis microalgae that entered the contaminant removal systemmay exit the vertical water chamber through an outlet and/or a returnpipe and may be recirculated to the V-Trough growing vessel to rejointhe algae culture.

In some embodiments, the method may further comprise subjecting thefluid containing the algae culture to further processing, harvesting,treatment or separation processes or devices such as, but not limited tocoagulation, flocculation, pH manipulation, filtering, dewatering, UVsterilization, and/or centrifugation, before entering the contaminantremoval system as described in the exemplary systems disclosed above. Insome embodiments, the method may further comprise subjecting the algaeculture medium fluid to further processing, harvesting, treatment orseparation processes or devices such as, but not limited to coagulation,flocculation, pH manipulation, filtering, dewatering, UV sterilization,and/or centrifugation, after exiting the contaminant removal system asdescribed in the exemplary systems disclosed above. In furtherembodiments, the method comprises a combination of further processesbefore and after the fluid enters the contaminant removal system.

In one exemplary embodiment of a method for increasing the growth rateof the liquid algae culture 110 in the vessel 105, wherein themicroalgae culture comprises microalgae cells and contaminants, themethod comprises coupling the contaminant removal system 100 to thevessel 105 containing the liquid algae culture 110, wherein the growthrate of the microalgae cells is progressively slowing; processing theliquid algae culture 110 in the vessel through the contaminant removalsystem 100, wherein at least a portion of the contaminants are removedduring processing; and returning at least a portion of the processedliquid algae culture 110 to the vessel 105 at least 10 times in a 24hour period, wherein the portion of the liquid algae culture 110returned to the vessel exhibits an increase in growth rate of themicroalgae cells of at least 5%. In one embodiment, the method forincreasing the growth rate of the liquid algae culture 110 in the vessel105 may remove the contaminants by foam fractionation. The contaminantremoval system 100 may inject a gas into the liquid algae culture 110 ata flow rate of approximately 1 LPM to approximately 10,000,000 LPM. Theflow rate of the liquid algae culture 110 through the contaminantremoval system 100 may be from approximately 1 lpm to approximately1,000,000 lpm.

In one exemplary embodiment of a method for improving the viability ofthe liquid algae culture 110 in the vessel 105, wherein the liquid algaeculture 110 comprises microalgae cells and contaminants, the methodcomprises: coupling the contaminant removal system 100 to the vessel 105containing the liquid algae culture 110, wherein the growth rate of themicroalgae cells is progressively slowing; processing the liquid algaeculture 110 in the vessel through the contaminant removal system 100,wherein at least a portion of the contaminants are removed duringprocessing; and returning at least a portion of the processed liquidalgae culture 110 to the vessel 105 at least 10 times in a 24 hourperiod, wherein the portion of the liquid algae culture 110 returned tothe vessel 105 exhibits an increase in the lifetime of the liquid algaeculture 110 of at least 5 days as compared to the lifetime of the liquidalgae culture 110 without processing. In one embodiment, the method forincreasing the growth rate of the liquid algae culture 110 in the vessel105 may remove the contaminants by foam fractionation. The contaminantremoval system 100 may inject a gas into the liquid algae culture 110 ata flow rate of approximately 1 LPM to approximately 10,000,000 LPM. Theflow rate of the liquid algae culture 110 through the contaminantremoval system 100 may be from approximately 1 lpm to approximately1,000,000 lpm.

The contaminant removal system can also be utilized for gas transfer inan biological reactor system. The contaminant removal system can removeand/or add oxygen (or any other type of gas in the reactor system) andincrease gas transfer across the air/water interface of the system. Insome embodiments, the contaminant removal system can be utilized for theremoval of oxygen from a closed photobioreactor system containing aphototrophic biological culture. The oxygen can be collected orharvested in the vertical chamber as the gas and liquid culture mixtureflow through contaminant removal system for utilization in otherco-products or as a source of energy. In other embodiments, thecontaminant removal system can be utilized for adding oxygen to amixotrophic or heterotrophic reactor system through gas injection.Mixotrophic and heterotrophic biological cultures differ fromphototrophic biological cultures in that a phototrophic culture utilizescarbon dioxide and light as energy sources to produce oxygen, whilemixotrophic and heterotrophic cultures can utilize a carbon substrateand oxygen as energy sources to produce carbon dioxide. Air, pure oxygenor a mix can be injected into the contaminant removal system to addoxygen to the biological culture returning to the mixotrophic orheterotrophic reactor system.

A universal contamination removal system can be designed and constructedto maximize the effects of gas transfer, contamination removal, andharvesting of the algae culture. The design of the contamination removalsystem can be customized for the intended application or a combinationof applications. The height and diameter/width-depth of thesubstantially vertical chamber can be sized to increase the gas transferexchange at the air water surface and dwell time. The dwell time of theliquid in the contamination removal system and gas velocity can beadjusted to increase or decrease the rate of gas transfer. The gasvelocity, water flow rate, dwell time within the contamination removalsystem, and surface area to volume ratio of the substantially verticalchamber (diameter/width-depth and height) can be adjusted to increase ordecrease gas transfer within the system.

In one non-limiting exemplary embodiment, a tubular, closedphotobioreactor system can have a contamination removal system sized andoperated for the addition or removal of a particular gas (in thisexample oxygen) from a biological reactor system. In a closedphotobioreactor oxygen concentration increases beyond saturation(>%300), which can be inhibitory and detrimental to the particular algaespecies that is being grow. The oxygen needs to be removed via some typeof gas transfer system. The customized contamination removal system canremove oxygen from the closed reactor system with the use of airinjection into the contamination removal system, and sufficient dwelltime and surface/volume ratio in the vertical chamber. The contaminationremoval system can be modified to enhance the gas transfer in thecontamination removal system while still maintaining the effects ofcontamination removal and/or harvesting. The unit can be runcontinuously or off of a feedback control via an oxygen sensor. The gasvelocity can be turned on or off, or adjusted according to the dissolvedoxygen level. The gas transfer of oxygen in the closed photobioreactorsystem is necessary to optimize growth of the algae culture. Thecombination of removing oxygen and contamination in the same system canefficiently enhance growth in the photobioreactor system. The settingsthat would be adjusted are the gas velocity, gas type and surface areato volume ratio of the substantially vertical chamber.

In another non-limiting exemplary embodiment the contamination removalsystem can be optimized to increase the dissolved oxygen content of theliquid in a mixotrophic or heterotrophic reactor system. Thecontamination removal system can utilize air or pure oxygen to increasethe dissolved oxygen content of the liquid. Oxygen levels below 2 mg/lin mixotrophic and heterotrophic reactor systems can be inhibitory anddetrimental to growth of the algae culture. It is necessary to maintainoxygen levels above 2 mg/l or higher to enhance growth. Thecontamination removal system can be customized to add oxygen to amixotrophic reactor system, remove contamination, and clean waterclarity. The settings that would be adjusted are the gas velocity, gastype and surface area to volume ratio of the substantially verticalchamber.

In a third non-limiting exemplary embodiment, both a phototrophic andmixotrophic reactor system can be run in tandem with a singlecontamination removal system. The phototrophic reactor system willsequester carbon dioxide and produce oxygen which can be removed fromthe liquid and collected by the contamination removal system. Carbondioxide can also be injected into the phototrophic culture as it flowthrough the contamination removal system to increase the amount ofcarbon dioxide dissolved in the phototrophic system. Once thecontaminant removal system switches over to flowing the mixotrophicculture through the contaminant removal system, the collected oxygen maybe injected into the mixotrophic culture to increase the amount ofoxygen dissolved in the mixotrophic system.

In a fourth non-limiting exemplary embodiment, both a phototrophic andmixotrophic system can be run in tandem with separate contaminationremoval systems. The phototrophic reactor system will sequester CO2 andproduce oxygen which can be stripped out of the liquid and collected bythe first contamination removal system. Carbon dioxide can also beinjected, in place of oxygen, to increase the amount of carbon dioxidedissolved in the phototrophic reactor system.

The oxygen stripped and collected by the first contamination removalsystem on the phototrophic reactor system can be fed into a secondcontamination removal system on the mixotrophic reactor system, whichrequires oxygen. This dual photo/mixo contamination removal system canalso be coupled to a third contamination removal system that controlsthe flow on both systems as needed via the use of feedback controlmechanism (dissolved oxygen, carbon dioxide, pH) and solenoid valves.

In the foregoing description, the invention has been described withreference to specific exemplary embodiments. Various modifications andchanges may be made, however, without departing from the scope of thepresent invention as set forth. The description and figures are to beregarded in an illustrative manner, rather than a restrictive one andall such modifications are intended to be included within the scope ofthe present invention. Accordingly, the scope of the invention should bedetermined by the generic embodiments described and their legalequivalents rather than by merely the specific examples described above.For example, the steps recited in any method or process embodiment maybe executed in any appropriate order and are not limited to the explicitorder presented in the specific examples. Additionally, the componentsand/or elements recited in any system embodiment may be combined in avariety of permutations to produce substantially the same result as thepresent invention and are accordingly not limited to the specificconfiguration recited in the specific examples.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments. Any benefit, advantage,solution to problems or any element that may cause any particularbenefit, advantage or solution to occur or to become more pronounced,however, is not to be construed as a critical, required or essentialfeature or component.

The terms “comprises”, “comprising”, or any variation thereof, areintended to reference a non-exclusive inclusion, such that a process,method, article, composition, system, or apparatus that comprises a listof elements does not include only those elements recited, but may alsoinclude other elements not expressly listed or inherent to such process,method, article, composition, system, or apparatus. Other combinationsand/or modifications of the above-described structures, arrangements,applications, proportions, elements, materials or components used in thepractice of the present invention, in addition to those not specificallyrecited, may be varied or otherwise particularly adapted to specificenvironments, manufacturing specifications, design parameters or otheroperating requirements without departing from the general principles ofthe same.

The present invention has been described above with reference to anexemplary embodiment. However, changes and modifications may be made tothe exemplary embodiment without departing from the scope of the presentinvention. These and other changes or modifications are intended to beincluded within the scope of the present invention.

1. A system for transferring gasses within a liquid culture comprising agrowth medium and at least one of a microalgae and a cyanobacteria in avessel, comprising: an inlet tube configured to receive the liquidculture in the vessel; a pump coupled to the inlet tube, wherein thepump is configured to receive the liquid culture and propel the liquidculture at a preselected liquid flow rate; a gas injector coupled to thepump and configured to inject a gas into the liquid culture in the pumpat a preselected gas flow rate, wherein the gas mixes with the liquidculture in the pump to produce a gas and liquid culture mixture: asubstantially vertical chamber configured to receive the gas and liquidculture mixture from the pump at a first end of the vertical chamber,wherein: the gas and liquid culture mixture is propelled from the firstend of the vertical chamber to a second end of the vertical chamber,wherein a dwell time is the time duration of the gas and liquid culturemixture within the inlet tube, pump and vertical chamber; and a foamcomprising the contaminants is generated when the gas and liquid culturemixture travels from the first end to the second end of the verticalchamber; and a collection container disposed at the second end of thevertical chamber and configured to separate and collect the foam,wherein the injection of gas and the dwell time create a transfer ofgasses within the gas and liquid culture mixture improves the growthrate of the at least one of the microalgae and the cyanobacteria.
 2. Thesystem of claim 1, wherein the preselected liquid flow rate is adaptedto adjust the dwell time to maximize the gas transfer within the gas andliquid culture mixture.
 3. The system of claim 2, wherein thepreselected liquid flow rate is from approximately 1 lpm toapproximately 1,000,000 lpm.
 4. The system of claim 2, wherein thepreselected liquid flow rate is from approximately 10 lpm toapproximately 10,000 lpm.
 5. The system of claim 1, wherein thepreselected gas flow rate is adapted to maximize the gas transfer withinthe gas and liquid culture mixture.
 6. The system of claim 5, whereinthe preselected gas flow rate is from approximately 1 LPM toapproximately 10,000,000 LPM.
 7. The system of claim 5, wherein thepreselected gas flow rate is from approximately 100 LPM to approximately100,000 LPM.
 8. The system of claim 1, wherein the vessel is a closedvessel comprising at least one of the microalgae and cyanobacteria whichproduce oxygen through photosynthesis in a phototrophic culture.
 9. Thesystem of claim 8, wherein the gas transfer comprises removing oxygenfrom the gas and liquid culture mixture.
 10. The system of claim 9,wherein the removal of oxygen reduces the oxygen concentration of thegas and liquid culture mixture below 300%.
 11. The system of claim 1,wherein the gas is at least one of air, ozone, nitrogen, flue gas,oxygen, and carbon dioxide.
 12. The system of claim 11, wherein at leastone of air and oxygen is injected into the gas and liquid culturemixture to increase a dissolved oxygen level of the gas and liquidculture mixture to above 2 mg/l.
 13. The system of claim 12, wherein thegas and liquid culture mixture comprises at least one of a heterotrophicand a mixotrophic culture.
 14. The system of claim 1, further comprisingan outlet tube coupled to the substantially vertical chamber andconfigured to receive the gas and liquid culture mixture in thesubstantially vertical chamber.
 15. The system of claim 14, wherein theoutlet tube is coupled to the vessel and returns the gas and liquidculture mixture into the vessel.
 16. A system for transferring gasseswithin a liquid culture comprising a growth medium and at least one of amicroalgae and a cyanobacteria in a vessel, comprising: an inlet tubeconfigured to receive the liquid culture in the vessel; a pump coupledto the inlet tube and configured to receive the liquid culture andpropel the liquid culture at a preselected liquid flow rate; a gasinjector coupled to the pump and configured to inject a gas into theliquid culture in the pump at a preselected gas flow rate, wherein thepreselected gas flow rate is adapted to aggregate the contaminants inthe liquid culture and the gas mixes with the liquid culture in the pumpto produce a gas and liquid culture mixture; a substantially verticalchamber configured to receive the gas and liquid culture mixture fromthe pump at a first end of the vertical chamber, wherein: the gas andliquid culture mixture is propelled from the first end of the verticalchamber to a second end of the vertical chamber, wherein a dwell time isthe time duration of the gas and liquid culture mixture within the inlettube, pump and vertical chamber; and a foam comprising the contaminantsis generated when the gas and liquid culture mixture travels from thefirst end to the second end of the vertical chamber a collectioncontainer disposed at the second end of the vertical chamber andconfigured to collect the foam; wherein the injection of gas and thedwell time create a transfer of gasses within the gas and liquid culturemixture which at least one of improves a growth rate and extends alifetime of the at least one of the microalgae and the cyanobacteriaupon returning the at least one of the microalgae and the cyanobacteriato the vessel for continued cultivation as compared to the growth rateand the lifetime prior to gas transfer.
 17. The system of claim 16,wherein the gas transfer comprises removing oxygen from a phototrophicgas and liquid culture mixture, wherein the oxygen is produced byphotosynthetic activity of at least one of the microalgae andcyanobacteria in a phototrophic culture.
 18. The system of claim 17,wherein the removed oxygen is injected into at least one of amixotrophic and a heterotrophic culture of microalgae or cyanobacteria.19. A system for transferring gasses within a liquid culture comprisinga growth medium and at least one of a microalgae and a cyanobacteria ina vessel, comprising: an inlet tube configured to receive the liquidculture in the vessel; a pump coupled to the inlet tube and configuredto receive the liquid culture and propel the liquid culture at apreselected liquid flow rate; a gas injector coupled to the pump andconfigured to inject ozone gas into the liquid culture in the pump at aconcentration of between about 0.01 mg/L to about 1.0 mg/L at apreselected gas flow rate, wherein the preselected gas flow rate isadapted to aggregate the contaminants in the liquid culture and the gasmixes with the liquid culture in the pump to produce a gas and liquidculture mixture; a substantially vertical chamber configured to receivethe gas and liquid culture mixture from the pump at a first end of thevertical chamber, wherein: the gas and liquid culture mixture ispropelled from the first end of the vertical chamber to a second end ofthe vertical chamber, wherein a dwell time is the time duration of thegas and liquid culture mixture within the inlet tube, pump and verticalchamber; and a foam comprising the contaminants is generated when thegas and liquid culture mixture travels from the first end to the secondend of the vertical chamber; a collection container disposed at thesecond end of the vertical chamber and configured collect the foam;wherein the injection of gas and the dwell time creates a transfer ofgasses within the gas and liquid culture mixture which at least one ofimproves a growth rate and extends a lifetime of the at least one of themicroalgae and the cyanobacteria upon returning the at least one of themicroalgae and the cyanobacteria to the vessel for continued cultivationas compared to the growth rate and the lifetime prior to gas transfer.20. The system of claim 19, wherein the gas injected is carbon dioxideand the injection increases a dissolved carbon dioxide level of the gasand liquid culture mixture.